There are many people that will charge you a lot of money to be able to disable the Microsoft program "Messenger". I'm not charging you a penny, you don't have to sign up for who knows what, and your homepage won't be switched.

Instructions:
(Please be patient while the pictures load.)
Step 1:
Click "Start", then "Control Panel".


Step 2:
Click on "Administrative Tools".


Step 3:
Click on the "Services" shortcut.


Step 4:
Find "Messenger" on the list and double-click on it.


Step 5:
Click "Stop".


Step 6:
Now you get to make a choice.  You can either select to change the Startup type to "Manual" or "Disabled".
Manual: Allows you to manually start up Messenger when you want to run it.
Disabled:Completely disables Messenger.
(Mine is set to “Manual” and has worked just fine for me.)


Step 7:
Click "Apply", click "OK", and you are done.


I hope you have found this information to be helpful and easy to use.

Note: I am running Windows XP and the instructions have worked for me thus far. As far as I know, NT and 2000 will follow the same instructions, but I'm not 100% sure just because I haven't tried it on a different operating system. If you know, send me an email at request@allenpages.com. I try to check my email regularly and will post any updates that I believe to be worthy.
Disclaimer Thingy: By following the instructions, Messenger will be disabled. I guess in the disclaimer I have to tell you, if you PC acts strangely after following my instructions or if my instructions don't work or whatever else may happen, it isn't my fault, blah blah blah...